A method or system of such a type is employed in the field of plant automation, in which a plurality of automation systems is generally employed for controlling or updating a plant. In this situation, an important partial aspect is the use of variables from one automation system in a different automation system. The program elements that make mutual use of common resources, such as variables for example, have a logical relationship through this shared usage. For this reason, changes in one location frequently also necessitate changes in other locations, for example if the meaning of a variable or the data type of a variable changes. In many cases the user must be able to modify the program locations of the originator and the user of a resource. To this end, he must be able to easily select these program locations, starting from one side, for example in order to be able to find, open, display and change the program locations in question. Since a resource can be used by a plurality of users, it is also necessary to exercise control over a plurality of users. This required functionality corresponds to a type of “cross-reference list” for the global use of resources across the automation system, allowing the relevant program elements to be called and/or displayed. In this situation, the resources are generally displayed, and any changes needed made, in an engineering system linked communicatively with the automation systems.
According to the prior art, the instances of use of variables can only be displayed in the context of a program of an automation system by way of the reference list and navigation is effected by way of the latter to the corresponding definition location and all application locations. There are no corresponding solutions relating to the use of a resource in a plurality of automation systems.
When using unilateral programmed function block communication, for example with PUT/GET or READ/WRITE in accordance with IEC 61131-5, the user must ascertain the communication partner from the properties of the connection for example. Here he must use the address or name to identify the local variable in the program here and can use the local reference list here to find the application locations. When using bilateral programmed function block communication, for example with USEND/URCV, the user must similarly first ascertain the communication partner from the properties of the connection for example. Here he must use the connection identifier here belonging to the connection and the parameter R_ID to find the corresponding instance. The local variable used is here, and he can use the local reference list here to find the application locations.